A light emitting diode (LED) has various advantages such as long lifetime, low power consumption, excellent initial driving characteristics, high vibration resistance, and high tolerance for repeated power interruption, over a filament-based light emitting diode device. Therefore, a demand for the LED is continuously increasing. In particular, since III group nitride semiconductor devices are capable of emitting light in a blue short wavelength area, they have been spotlighted in the recent years.
In the case of a nitride light emitting diode, light is generated in an activation layer and is emitted to the outside through a nitride semiconductor. However, since a critical angle at the boundary between a semiconductor layer and air is small, considerable amount of light is not emitted to the outside of the nitride semiconductor layer.
Additionally, in the case of a lateral light emitting diode, current spreading is blocked due to a high resistance of a p-electrode to cause unbalance of current flow. The unbalance of current flow results in current crowding effect. Since the current crowding effect causes non-uniform light emission of an activation layer, it is difficult to increase a size and power of a device.